The Story: I purchased a Quaife QDF-11L differential for my 350z open differential and ran into the same issue as a previous member ( https://my350z.com/forum/engine-and-...d-install.html ). The Ring Gear bolt holes on the Quaife ring gear flange were too small for the bolts. I started an email dialog with Scott Cole of Motovicity Distribution (Quaife Distributor for US) and he stated that he hadn’t heard about this issue before. Ok, working with Scott and providing him info, the Quaife bolt holes measured out at 0.510” diameter. From the drawing on their web site, they should have been 0.522”. He checked all the QDF-11L differentials he had on the shelf as did Quaife Engineering in the UK. The bolt holes were the same 0.510” as mine.

The Problem: Bottom line is for this last production run, all the ring gear holes for the QDF-11L model were drilled with the wrong diameter.

Since the last production run was pretty long ago, the company is wondering why it hasn’t come to their attention before in force. My theories are: 1. People who purchased this differential, still have them sitting in the garage uninstalled. 2. During the installation with their car torn apart, they opened up the bolt holes instead of waiting and going through the long process of getting it fixed like I did. The fix for mine was a new ring gear flange with the correct bolt hole diameters. I am going to swap it out when it arrives.

The Solution: If you have purchased a QDF-11L and have not installed it yet, or you are going to order one, open the box up and check the diameter of the ring gear bolt holes. If they are 0.510” in diameter, then you have a differential from the last production run. Contact Quaife at their website http://quaifelsd.com/Default.aspx to start the dialog with Scott about getting your differential fixed. With a little dialog and some patience, I am very satisfied with Quaife and their response. Hope your experience is the same.

 

Man glad my qdf-11l didn't have issues. Bought mine thru thmotorsports about 9 months ago.

 

Thanks for that info wwilde. My email has been sent.

 

i'm glad you're satisfied with their customer service, cause I am not. In a nutshell, me and scott are 22 days and 8 emails deep in this discussion about my bolt holes being too small, and he has yet to admit that a manufacturer error occurred. Pictures of the differential serial number, pictures of measurements and a picture of a differential bolt not fitting have all been sent to him but an answer about fixing the issue has yet to be given to me.

 

Same here, bought mine at thmotorsports around the same time and didn't have any issues putting mine in.

There would have been a lot of cursing had I discovered that issue with the stock diff already opened up.

 

Mine is working like a champ. So it would have been obvious that it was .510" and would not have worked right? Also purchased through THMotorsports.

 

I just shipped my original ring gear flange back to Scott at Quaife. Hopefully he will open up the holes to the correct diameter on this one and ship it out to you so that you can swap yours like I did mine. Sorry to hear about the poor service. I suspect if Quaife actually admitted an error was made, that they would have to do a recall or something. Hope it works out for you. It did take about three weeks to get everything taken care of.

 

Good info. BOTTOM LINE. If purchasing a QDF-11L have the seller measure the bolt holes to make sure they are .522" and not the faulty .51"

 

What's the big deal? I mean yeah it is wrong and they should fix it and i would be pissed too, but it you are savvy enough to swap the diff in your car, can't you drill out a couple holes .012"? Granted it would be an odd side drill bit or reamer but you should be able to find something at MSC (13.3 mm?). I just don't see the point in waiting months for a fix when you could fix it yourself and get it back on the road in less than a week. If the holes were too large, it would be a different story...